1. Field of the Invention
The present invention generally relates to a touch panel having resistance films facing each other, and an input device and an electronic apparatus each equipped with the touch panel, and more particularly, to a touch panel having an antenna for short-distance wireless data communication, and an input device and an electronic apparatus each equipped with the touch panel.
2. Description of the Related Art
In recent years, short-distance wireless data communication techniques such as wireless LAN (local area network) and Bluetooth (trade name) have been developed. These techniques are greatly expected to provide interfaces for connecting mobile devices to one another, or connecting mobile devices to stationary electronic apparatuses.
However, the mobile devices such as portable telephones and PDAs (Personal Digital Assistants) have become too small, as the technology has dramatically advanced. Also, there is an increasing demand in the market for smaller mobile devices with higher performance. In this trend, it is difficult to secure a large enough space for a high gain antenna of wireless data communication.
To solve the above problem, Japanese Unexamined Patent Publication No. 5-189191 discloses a structure in which an antenna is mounted on a display device such as a liquid crystal display.
Referring to FIGS. 1A and 1B, a structure having a flat antenna 110 provided on the back surface of a flat display device 100. FIG. 1A is a perspective view illustrating the front surface of the flat display device 100. FIG. 1B is a perspective view illustrating the back surface (the side with the antenna) of the flat display device 100. As shown in FIGS. 1A and 1B, the flat display device 100 includes a LCD (Liquid Crystal Display) 101, a transmit/receive (TX/RX) unit 102, a battery 103, and the flat antenna 110 that is a bent lead-wire antenna provided on the opposite side to the other three components. Accordingly, the space for accommodating antenna can be made small by this conventional technique.
In a case where the display unit also serves as an input device of touch panel type, such as the display unit of a PDA, an antenna can be mounted in the same manner as the above. Japanese Unexamined Patent Publication No. 2002-215330, for example, discloses such a structure.
Referring now to FIG. 2, a structure having an antenna wire 210 provided on a touch panel device 200 will be described. FIG. 2 only shows the layer on which the antennal wire 210 is provided in the touch panel device 200 having a multi-layer structure. As shown in FIG. 2, the touch panel device 200 has the antenna wire 210 that is brought into contact with electrodes on an upper layer (or a lower layer) by a user pressing the touch panel. This antenna wire 210 is formed along the outer periphery of a substrate 201 on which electrically connected transparent electrodes (made of ITO; Indium Tin Oxide) 202 and 203 are provided. Accordingly, the space for accommodating another antenna can also be made small by this conventional technique.
With either of the above conventional techniques, however, there is a problem that the size increase due to the addition of an antenna cannot be avoided. With the above conventional structures, there is another problem that, as electromagnetic wave stays within the device due to the antenna formed on the back surface of the device, only a reduced effect can be achieved. There is yet another problem that sufficient gain cannot be obtained with a wire-type antenna.